Is that fact or political opinion? ED is much more accessable by bus and train than many areas of Southwark, thus increasing the chances of offenders being able to make their appointments. Additionally, being outside of zone 1 it is cheaper for them to travel there, again raising engagement, and minimising the council's outlay in reimbursing fares. There is also many social studies that indicate that individuals raise their behaviour to their environment. Having such a service in East Dulwich instead of Old Kent Rd for instance, is likely to have a beneficial impact on the behaviour of the service's client group. See what I did there?